Summary: In this assignment, you will have the opportunity
to develop two simple Web services in Scheme.
Assigned: Friday, 28 February 2003
Due: Friday, 7 March 2003
Key Topics: Recursion, string manipulation, Web
services.
Turning it in: Email me the MathLAN address of all the
files needed for your assignment.
Collaboration: You may work in groups of up to size
three. You may discuss the assignment with anyone you wish. You must
cite anyone with whom you discuss this assignment.
Citations: The Bizz-Buzz problem is based on a problem
that Ben Gum wrote for CSC151. On 18 February 2003, it was available as
Exercise 9 of
http://www.math.grinnell.edu/~gum/courses/151/labs/recursion-with-integers.xhtml. The remainder of the assignment is based on a similar
assignment I wrote for CSC153 (but with this assignment in mind).
Useful Files:
Contents:
Implement two of the three following Web services:
In the summer of 2002, I drove a group of ten-or-so Grinnell students
to Denver. In the long-seeming trip, they shared as many silly word
games as they could come up with. One such game was Bizz Buzz
Here's my understanding of the game.
- You pick a single-digit number, which we'll call the buzzer.
- You start counting.
- Whenever you hit a number that ends with the digit, you say
bizz
instead of that number.
- Whenever you hit a number that is evenly divisible by the single-digit
number, you say
buzz
instead of that number.
- Whenever you hit a number this ends with the digit and is evenly
divisible by the single-digit number, you say
bizz buzz
instead
of that number.
For example, if the buzzer were 3, the sequence would be: 1, 2, bizz buzz,
4, 5, buzz, 7, 8, buzz, 10, 11, buzz, bizz, 14, buzz, 16, 17, buzz,
19, 20, buzz, 22, bizz, buzz, 25, 26, buzz, 28, 29, buzz, 31, 32,
bizz buzz, ....
One strategy for putting Bizz Buzz on the Web is to write a page
that prints out the Bizz-Buzz sequence starting with some number and
ending with some number. In this case, the primary input page will
need to take three inputs: the buzzer, the starting value, and the
ending value.
You can visit an example
of this strategy (which fails to actually report on the steps in
Bizz Buzz).
Another strategy for putting Bizz Buzz on the Web is to write a script
that does one value each time it is loaded, and moves on to the next value
when it is loaded again (and again and again and ...).
You can visit an example
of this strategy (which once again fails to actually report on the steps
in Bizz Buzz).
Pick one of the two implementation strategies. Make copies of the
appropriate files. Update them so that they correctly play Bizz-Buzz.
1. Extend Bizz-Buzz in some interesting way.
One example is Bizz-Buzz-Fizz-Fuzz, a game very much like Bizz-Buzz except
that it has a fuzzer as well as a buzzer. When the current number is
a multiple of the fuzzer, you say Fizz
. When the current number
ends with the fuzzer, you say Fuzz
. You can figure out the rest.
2. Combine the two implementation strategies in an interesting way.
For example, you might allow someone to select how many steps are
shown on each page in sequence.
3. Make it look nicer. (This will only earn you a little extra credit,
but might give you a lot of satisfaction.)
4. Come up with something else on your own.
Nile.com is a new competitor for a well-known online book store. They'd
like their Web site to include a book recommendation service. Unfortunately,
they don't know many good programmers. However, they're fairly clever
enough to realize that they might convince a naive professor (that's me)
to assign their service to his students.
I'm so naive that I've even started the interface, which you
can find at http://www.cs.grinnell.edu/~rebelsky/Courses/CS151/2003S/Examples/nile.com.html,
and the corresponding Scheme script, which you can find at.
http://www.cs.grinnell.edu/~rebelsky/Courses/CS151/2003S/Examples/nile.com.ss. I do want you to write
something, so I've left the select-book procedure with
an incredibly stupid definition.
It is your responsibility to finish the select-book
procedure. Your procedure should step through the list of books,
evaluating each in turn. It should return the best match for the
reader's selections. What's the best match? The one with the
most adjectives in the list of likes and the fewest in the list of
dislikes. You get to decide how to combine those two factors.
1. Make the service more useful (e.g., by returning a set of top
matches, rather than a single top match).
2. Allow a greater range of choices (e.g., by allowing the user to rank
each attribute on a scale of 1 to 5). Note that just adding a few more
adjectives does not count.
3. Make it look nicer. (This will only earn you a little extra credit,
but might give you a lot of satisfaction.)
4. Find some other way to extend the service.
Extend your Mad Lib from homework 2
so that it automatically fills in random
(but appropriate) words
for the different components. That is, someone will simply click a
Tell me a story
(or Write me a poem
or ...) button and
they'll get a Web page that differs each time.
How will you write this service? Instead of getting the various word
forms using get-cgi-variable, you can instead select between
different words in a list using the following procedure (which we'll
discuss again later in the semester).
;;; Procedure:
;;; random-element
;;; Parameters:
;;; lst, a list
;;; Purpose:
;;; "Randomly" select an element of lst.
;;; Produces:
;;; val, a value.
;;; Preconditions:
;;; lst is nonempty.
;;; Postconditions:
;;; val is an element of lst.
;;; It is comparatively difficult to predict which element of
;;; lst val is.
(define random-element
(lambda (lst)
(list-ref lst (random (length lst)))))
Here's a quick example of random-element in practice.
> (random-element (list "red" "orange" "yellow" "green" "blue"))
"yellow"
> (random-element (list "red" "orange" "yellow" "green" "blue"))
"orange"
> (random-element (list "red" "orange" "yellow" "green" "blue"))
"orange"
> (random-element (list "red" "orange" "yellow" "green" "blue"))
"green"
> (random-element (list "red" "orange" "yellow" "green" "blue"))
"yellow"
> (random-element (list "red" "orange" "yellow" "green" "blue"))
"blue"
> (random-element (list "red" "orange" "yellow" "green" "blue"))
"yellow"
> (random-element (list "red" "orange" "yellow" "green" "blue"))
"red"
For extra credit, do particularly interesting things. For example, you
might configure your program to choose rhyming words, to generate phrases
with a certain number of syllables (but which don't always have the same
form), that select between different sentence forms, and so on and so forth.
Wednesday, 19 February 2003 [Samuel A. Rebelsky]
- Designed.
- Began to write.
Thursday, 20 February 2003 [Samuel A. Rebelsky]
Thursday, 27 Febraury 2003 [Samuel A. Rebelsky]
- Rewrote slightly for CSC151.
Friday, 28 February 2003 [Samuel A. Rebelsky]
- Added the
Writer
Web service (and allowed students to pick two of
three).
- Released.
Thursday, 6 February 2003 [Samuel A. Rebelsky]
;
Check with Bobby